/*
 * Copyright [2020] [MaxKey of copyright http://www.maxkey.top]
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 

package org.maxkey.crypto;
    import java.io.FileInputStream;
    import java.io.ObjectInputStream;
    import java.security.Key;
    import java.security.PrivateKey;
    import java.security.PublicKey;
    import java.security.Signature;
    import java.security.interfaces.RSAPrivateKey;
    import java.security.interfaces.RSAPublicKey;

    import javax.crypto.Cipher;
    
    
    /**
    * RSA�ӽ���,RSAǩ��ǩ����֤��
    *
    * @author Administrator
    *
    */
    public class RsaMessage {




    public static void main(String[] args) throws Exception {
    String str = "hello,�����ĵ����";
    System.out.println("ԭ�ģ�" + str);

    RsaMessage rsa = new RsaMessage();
    RSAPrivateKey privateKey = (RSAPrivateKey) rsa.readFromFile("sk.dat");
    RSAPublicKey publickKey = (RSAPublicKey) rsa.readFromFile("pk.dat");

    byte[] encbyte = rsa.encrypt(str, privateKey);
    System.out.println("˽Կ���ܺ�");
    String encStr = toHexString(encbyte);
    System.out.println(encStr);

    byte[] signBytes = rsa.sign(str, privateKey);
    System.out.println("ǩ��ֵ��");
    String signStr = toHexString(signBytes);
    System.out.println(signStr);

    byte[] decByte = rsa.decrypt(encStr, publickKey);
    System.out.println("��Կ���ܺ�");
    String decStr = new String(decByte);
    System.out.println(decStr);

    if (rsa.verifySign(str, signStr, publickKey)) {
    System.out.println("rsa sign check success");
    } else {
    System.out.println("rsa sign check failure");
    }
    }

    /**
    * ����,key�����ǹ�Կ��Ҳ������˽Կ
    *
    * @param message
    * @return
    * @throws Exception
    */
    public byte[] encrypt(String message, Key key) throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.ENCRYPT_MODE, key);
    return cipher.doFinal(message.getBytes());
    }

    /**
    * ���ܣ�key�����ǹ�Կ��Ҳ������˽Կ������ǹ�Կ���ܾ���˽Կ���ܣ���֮��Ȼ
    *
    * @param message
    * @return
    * @throws Exception
    */
    public byte[] decrypt(String message, Key key) throws Exception {
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.DECRYPT_MODE, key);
    return cipher.doFinal(toBytes(message));
    }

    /**
    * ��˽Կǩ��
    *
    * @param message
    * @param key
    * @return
    * @throws Exception
    */
    public byte[] sign(String message, PrivateKey key) throws Exception {
    Signature signetcheck = Signature.getInstance("MD5withRSA");
    signetcheck.initSign(key);
    signetcheck.update(message.getBytes("ISO-8859-1"));
    return signetcheck.sign();
    }

    /**
    * �ù�Կ��֤ǩ�����ȷ��
    *
    * @param message
    * @param signStr
    * @return
    * @throws Exception
    */
    public boolean verifySign(String message, String signStr, PublicKey key)
    throws Exception {
    if (message == null || signStr == null || key == null) {
    return false;
    }
    Signature signetcheck = Signature.getInstance("MD5withRSA");
    signetcheck.initVerify(key);
    signetcheck.update(message.getBytes("ISO-8859-1"));
    return signetcheck.verify(toBytes(signStr));
    }

    /**
    * ���ļ���ȡobject
    *
    * @param fileName
    * @return
    * @throws Exception
    */
    private Object readFromFile(String fileName) throws Exception {
    ObjectInputStream input = new ObjectInputStream(new FileInputStream(
    fileName));
    Object obj = input.readObject();
    input.close();
    return obj;
    }

    public static String toHexString(byte[] b) {
    StringBuilder sb = new StringBuilder(b.length * 2);
    for (int i = 0; i < b.length; i++) {
    sb.append(HEXCHAR[(b[i] & 0xf0) >>> 4]);
    sb.append(HEXCHAR[b[i] & 0x0f]);
    }
    return sb.toString();
    }

    public static final byte[] toBytes(String s) {
    byte[] bytes;
    bytes = new byte[s.length() / 2];
    for (int i = 0; i < bytes.length; i++) {
    bytes[i] = (byte) Integer.parseInt(s.substring(2 * i, 2 * i + 2),
    16);
    }
    return bytes;
    }

    private static char[] HEXCHAR = { '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
    }
